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Old 02-07-2013, 10:24 PM   #781
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Marin, you are forgetting that there are DeFevers out there with electric get home motors..........would those technically be twins?
They have two propellers so in that sense they are twins. But they are not twins in the sense that our GB is a twin because the two props are not of equal size, positioned equidistant from the keel or centerline, or powered by engines developing equal power. Therefore one cannot perform the same kind of maneuvers using differential thrust (and rudders and power) that one can perform with an actual twin-engine boat.
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Old 02-07-2013, 10:25 PM   #782
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Not sure if Alco made an opposed piston engine. May have, they sure built a lot of diesels. I learned on a Fairbanks Morse, which had some use on locomotives as well.
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Old 02-07-2013, 10:25 PM   #783
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Correct ... Fairbanks-Morse.
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Old 02-07-2013, 10:35 PM   #784
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Many nineteenth-century ships with engines carried sail rigs for "get-home" propulsion in case of engine failure.
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Old 02-07-2013, 10:35 PM   #785
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ALCO made it's own diesel engines by virtue of buying an established diesel engine manufacturing company in 1929 or thereabouts. To my knowledge the engines made for ALCO's diesel-electric locomotives by this company were all conventional designs.
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Old 02-07-2013, 10:38 PM   #786
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I'll have to look that up. Sounds interesting. I used to work on 8 cylinder, 16 piston diesel engines. Rick probably did too, if I recall his background correctly.
I cant find the link. but this is similiar except that it uses four pisrones in teo cylinders. The one that impressed me used two pistonsw which fired both up and down making the two cylinders into four. The piston top and bottom were the dame and the wrist pins extended to operate rods to the crank

EcoMotors OPOC Two Stroke Engines – Opposed Piston Opposed Cylinder
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Old 02-07-2013, 11:41 PM   #787
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That's the same basic layout the Fairbanks-Morse of WWII had. You said in your first post that this new engine had one piston traveling back and forth in a single cylinder, thus creating two combustion chambers.

But apparently that's not the case. If it's the way your second post describes it, this is nothing new at all but dates back to the 1930s.
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Old 02-08-2013, 12:05 AM   #788
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Similar, but not the same. The Fairbanks Morse D8 1/8 had two parallel crankshafts. Fewer moving parts. The lower crank was timed 12 degrees ahead of the upper crank in timing so less hp went to the upper crank. The upper crank drove the scavanging blower. The lower crank was the prime mover, in my case it was a generator and the fuel racks were controlled by a synchronous governor. No valves just ports. Great design.
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Old 02-08-2013, 05:11 AM   #789
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this is nothing new at all but dates back to the 1930s.
Here is a quick review: http://www.mikalsen.eu/papers/FPEreview.pdf

Here is a Russian application used as an air compressor:
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Old 02-08-2013, 05:15 AM   #790
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The OP idea goes back a lot further than the 1930s. The first one was patented in 1907.

The Junkers predates FMs by a few years, the Jumo was flying in 1932 but FM didn't build an OP until 1938. There are quite few variants on the OP theme, some of the most exotic come from the Brits, of course.

Any engine fanatic would love to have worked for Napier, which appears to have been founded by a bunch of bored watchmakers who wished there was a way to convert oil to heat, smoke, and noise with as many parts as possible.
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Old 02-08-2013, 05:31 AM   #791
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Rick probably did too, if I recall his background correctly.
Oh man, much misery and many many laughs nursing FMs through snorkeling and equalizers. It was the only engine I ever had "runaway."

There are some great sea stories based on those beasts. I couldn't find it on this computer but I have a scan someplace of a photo of a very young me sitting on the log desk trying to capture some air. It shows a good view of the inboard exhaust valve and a "coffin cover." When I have time I'll dig it out, would make a good avatar.
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Old 02-08-2013, 10:09 AM   #792
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There was an English company named Doxford that built those things and powered half the merchant shipping fleet for decades ... there is nothing new in the engine room, just different ways of doing the same thing.
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Old 02-08-2013, 04:11 PM   #793
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That's the same basic layout the Fairbanks-Morse of WWII had. You said in your first post that this new engine had one piston traveling back and forth in a single cylinder, thus creating two combustion chambers.

But apparently that's not the case. If it's the way your second post describes it, this is nothing new at all but dates back to the 1930s.
Marin, the engine i refered to I cant find the link to. I just discovered it a couple of days ago and thought i had saved it but cant find it. These are two0 diferent engines crrect. I cant find the links anywhere.
ok, it worked like this.each cylinder was closed at each end and each end had intake and exhaust valves. In side the cylinder there was a single piston that was the same on the top as the bottom. The center of the cylinder was slotted to allow rods to be connected to the piston sorta risk pin like for crank operation. The other engine i found that was interesting was this one http://www.engineeringtv.com/video/O...posed-Cylinder
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Old 02-08-2013, 04:38 PM   #794
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Marin, the engine i refered to I cant find the link to. I just discovered it a couple of days ago and thought i had saved it but cant find it.

Was it not this one?

Watch "Opposed Piston Opposed Cylinder Engine" Video at Engineering TV

It is just another Doxford to me.
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Old 02-08-2013, 05:36 PM   #795
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Was it not this one?

Watch "Opposed Piston Opposed Cylinder Engine" Video at Engineering TV

It is just another Doxford to me.
Thats one of the two neat engines i found but the one I was most interested in was basically a two cylinder single piston engine. The piuston was the same on each end and the wrist pin drove the crank. This engine upon ignition it was compressing on the way down then it would ignite on the other end back and forth. Think of a single piston with a top on both the top and bottom with each end in its own cylinder.

Anyway Rick, check out this interesting link which has tons of descriptions of many diferent engine designs on the right side of the page.
Opposing piston 80% thermally efficient NASA Dreamer3000′s Weblog
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Old 02-10-2013, 08:25 AM   #796
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The need for really efficient multi fuel drone engines will create enough R&D ca$h to better the future of boats and noisemaker in time.

GO DARPA!
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Old 02-10-2013, 07:07 PM   #797
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The need for really efficient multi fuel drone engines will create enough R&D ca$h to better the future of boats and noisemaker in time.

GO DARPA!
that would be nice
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Old 02-11-2013, 06:43 AM   #798
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The "big boys" with the large single engines pushing an oil bucket have efficiencies we can only dream of .

Just getting near existing tanker efficiency would be an improvement.
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Old 02-11-2013, 07:20 AM   #799
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In terms of BSFC, we are only about 10 percent off. Considering how inexpensive and zero maintenance our engines are, that is pretty good.

Depending on the size of engine the BSFC figures overlap even in automotive applications.

The only place you will see over 50 percent thermal efficiency is on the very large slow speed 2-stroke engines.
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Old 03-27-2013, 07:55 AM   #800
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1 engine vs 2 engines

Hi Guys
For the last 30 years I have being sailing on sailboats, and because I`m moving to Fort Myers where I have an apartment with a dock included, that only accept up to 5`0 draftI So I sold my 52 Amel Supermaramu. Now I`m looking to buy a power boat, trawler, or similar. Because I`m ignorant on this matter the first question is: One Engine or two engines.Y will be concentrated in the ICW, or Bahamas.I had in mine Mainship or Grand Banks type.
Any suggestion are really welcome.
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